DONALD L. SPARKS is the Unidel S. Hallock du Pont Chair and Francis Alison Professor at the University of Delaware. He is internationally recognized for his research in the areas of kinetics of biogeochemical processes and surface chemistry of natural materials. His research has focused on fate and transport of trace metals in soil and water, soil remediation, water quality, and carbon sequestration in soils. Dr. Sparks is the author of two previous editions of Environmental Soil Chemistry and more than 350 refereed papers and book chapters. He is fellow of five scientific societies, and he has been the recipient of major awards and lectureships including the Geochemistry Medal from the American Chemical Society, the Liebig Medal from the International Union of Soil Sciences, the Einstein Professorship from the Chinese Academy of Sciences and the Philippe Duchaufour Medal from the European Geosciences Union. Dr. Sparks served as president of the Soil Science Society of America and the International Union of Soil Sciences, has served on advisory committees for several national laboratories and national and international centers and institutes, and served as chair of the U.S. National Academy of Sciences (NAS) Committee for Soil Sciences and other NAS Committees. Balwant Singh is Professor of Soil Science at the University of Sydney. He has over 35 years of research and teaching experience in Australia, India, the UK and the USA. His research interests include understanding the structural and chemical properties of soil clay minerals, adsorption reactions of trace elements at the mineral-water interface, phytoremediation of toxic elements, biochar and organic carbon interaction with soil minerals, and micronutrients availability in soils. Dr Singh has co-edited two books (Biochar: A Guide to Analytical Methods and Synchrotron-based techniques in Soils and Sediments) and over 200 research papers and book chapters. Elsevier, Burlington, USA. He is fellow of four scientific societies and recipient of various awards including The Marion L. and Chrystie M. Jackson Soil Science Award by the Soil Science Society of America and Marion L. and Chrystie M. Jackson Mid-Career Clay Scientist Award by Clay Minerals Society. Dr Singh has served as a Chair of the Soil Mineralogy Commission of International Union of Soil Sciences, President of the Australian Clay Minerals Society and President of the Australian Society of Soil Science, NSW Branch. Matthew G. Siebecker is an Assistant Professor of Applied Environmental Soil Chemistry at Texas Tech University. He was a postdoctoral researcher at the University of Delaware. Broadly, his research interests focus on the chemical reactions that take place between dissolved ions and molecules and the solid components of soil, including clay mineral, metal oxides, and soil organic matter. These reactions include adsorption, desorption, dissolution, surface precipitation, and redox. Dr. Siebecker is especially interested in the rapid formation of surface precipitates that are enriched with trace metals. The main themes of his research include the cycling of heavy metal contaminants and plant nutrients in soil and mineral systems, as well as the impacts of climate change and the application of animal waste products on soil. He has expertise in both the traditional wet-chemical laboratory techniques as well as advanced synchrotron-based techniques used in soil chemical research, and he has developed research collaborations internationally with scientists in Australia, Brazil, China, Costa Rica, France, and Italy. At Texas Tech University, Dr. Siebecker teaches an introductory undergraduate soils course entitled Urban Soils as well as an advanced upper-level course entitled Environmental Soil Chemistry course. He is an active member of the American Chemical Society and the Soil Science Society of America.
